The epimysium is the outermost connective tissue sheath of skeletal muscle, surrounding the entire muscle (organ). It is a dense irregular connective tissue, predominantly composed of type I collagen fibers. It helps to define the muscle's volume and prevents friction between neighboring muscles.
The epimysium is continuous with the perimysium and endomysium deep to it, and all three layers converge and blend with the connective tissue of the muscle's tendon. During muscle contractions, muscle fibers will pull on these connective tissue sheaths, which will in turn transmit the force to the bone that the tendon is inserting into to produce movement. If the muscle does not have a tendon of insertion and instead inserts directly onto bone, the epimysium will blend into the periosteum of the bone. Epimysium can sometimes also blend with the deep fascia between adjacent muscles, or even the superficial fascia.
Blood vessels and nerve fibers also pierce the epimysium to supply the muscle.
|Dense irregular connective tissue; predominantly type I collagen, some elastin.
|Surrounding an entire skeletal muscle organ
Learn more about skeletal muscles in this study unit:
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